Gateway → OpenCode integration

Goal: every model the gateway serves appears in OpenCode's /model picker, under an ID that says which upstream it came from, with limits that reflect reality — and when something is missing, you know which of six failure classes it is.

Read this first. Nearly every wasted hour in this domain comes from doing one of these in the wrong order. Discover, then wire, then attribute, then limit, then verify.

Non-negotiable rules